1. Field of the Invention
The present invention relates to an elevating apparatus for a working apparatus that will be mounted on a saddled working car such as a tractor.
2. Description of the Prior Art
Generally, elevation of a ground working apparatus for agriculture and construction by a saddled working car such as a tractor is carried out practically by hydraulic cylinders mounted on the front and the rear of the car body.
Selection for operating the front and rear hydraulic cylinders for actuating the ground working apparatus in the saddled working car has been performed by the operation of a change-over lever provided with a hydraulic pressure apparatus, and controlling the hydraulic cylinders to the elevation operation or the neutral state. That is, use of lifting apparatuses for elevating various ground working apparatuses has been carried out by an elevating lever that is provided separately from the change-over lever of the hydraulic pressure control apparatus.
The connecting mechanism for connecting the change-over lever and the elevating lever is such that a coiled spring is arranged between the change-over lever and the elevating lever wherein the movement of the change-over lever is transmitted to the elevating lever. The prior spring arranged between the change-over lever and the elevating lever has anchoring sections in the shape of a ring that are directly engaged with parts such as stubs or through-holes so that the expansion and contraction of the spring may be directly transmitted to the change-over lever and the elevating lever.
Further, the anchoring sections of the coiled spring has the opposite extended ends in the shape of a letter C.
Since in the prior hydraulic pressure control apparatus for operating a ground working apparatus, the change-over lever is operated to select either the front hydraulic cylinder or the rear hydraulic cylinder, and the elevation of the lifting apparatus of the selected hydraulic cylinder is also effected by the elevating lever provided separately from the change-over lever, the operation of the levers is quite complicated.
Further, if the front hydraulic cylinder is selected by the change-over lever and the link arms of the front hydraulic cylinder are elevated by the operation of the elevating lever, since the spring connecting the change-over lever and the elevating lever has the anchoring sections attached directly to the parts of the change-over lever and the elevating lever, the movement of the change-over lever is transmitted temporarily to the elevating lever via the expansion or contraction of the spring, and therefore the elevating lever that is otherwise in a state requiring no change-over is pulled back to the neutral state by the spring if the elevating lever is in the elevation state.
In the prior art, to allow the spring to act as a connecting mechanism between the levers, the change-over operation of the change-over lever or the elevating lever is prevented by adjusting strictly the rotational friction of the levers and the resilient force of the spring from being transmitted to the other lever, even if the spring is pulled by a certain degree of force. Alternatively, a stopper or the like is arranged to prevent undesired interaction and if the interaction is required, the stopper is released to allow the spring to act as a connecting mechanism.
In the case where a spring is arranged between the change-over lever and the elevating lever, since the anchoring sections of the spring are C-shaped and are small enough to be passed through or fitted to through-holes, stubs or the like formed to the levers, attachment of the anchoring sections to the through-holes, stubs or the like has been difficult and the anchoring sections are liable to be disengaged.
Further, the prior hydraulic pressure control apparatus for operating the working apparatus of a ground working car is required to have a change-over lever for selecting one of the front hydraulic cylinder and the rear hydraulic cylinder and an elevating lever for elevating the lifting apparatus of the selected hydraulic cylinder. Thus, their operations have to be carried out separately and are complicated, and since the hydraulic pressure control apparatus must have separate levers for the operation of the selection of the hydraulic cylinders and the elevation of the lifting apparatus, the production cost of the hydraulic pressure control apparatus becomes high and the production and the assembling thereof are difficult. Further, in some cases, a hydraulic cylinder is mounted only on one of the front and rear sections of a working car, and even in such a case, the hydraulic pressure control apparatus is usually provided with a change-over lever for selecting a hydraulic cylinder.